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Custom IQ - ASK & PSK & QAM

The Custom IQ Type: APSK & PSK & QAM waveform setup allows you to configure a frame with multiple data segments and/or idle segments. For each data segment, the modulation type can be further configured using a graphical constellation settings editor.

Quick Setups

Use this drop-down menu to select a modulation type from several supported formats. A single data segment using that modulation type appears in the segment list below. Click the cell in the Constellation column to open the Constellation Setting window, providing a graphical display and editing features (video). Quick setups enable you to configure complex signals for signal generation, equivalent to 89600B VSA setups in signal analysis.

Quick Setups IQ Settings

* For APCO25 CQPSK and ARIB T98/T61, the ALC is set to off to achieve better EVM. For all other cases, the ALC is on.

Save to 89600 VSA Setup

This feature saves the Custom IQ configuration as an 89600B VSA setup file, making it easier to configure complex constellations, such as 256APSK.

For added convenience, you can save the VSA setup as a quick setup in the VSA's Custom IQ Demod Property window. To do this, recall the Signal Studio VSA setup file, perform the measurement, and then click Save As Quick Setup. Now, whenever you click Quick Setups, you will find your previously saved setup listed among the other setups provided with the VSA software. Using this method, you no longer need to recall the Signal Studio VSA setup file each time you want to perform a measurement.

1. Custom IQ Selection

Custom IQ Type

Choices: ASK & PSK & QAM | FSK | SOQPSK | ARTM Multi-h CPM | Analog Modulation | Radar | Channel Sounding

Default: ASK & PSK & QAM

Select the type of Custom IQ.

2. Custom ASK PSK QAM Settings

Symbol Rate

Range: 1 kSa/s to 100 GSa/s

Default: 1 MSa/s

Sets the symbol rate of the waveform.

Filter

Choices: Low Pass| Gaussian | Root Nyquist | Nyquist | Rectangle | APCO25 HDQPSK | Half Sine | User Defined

Default: Root Nyquist

Select the filter type to be applied to the waveform.

Alpha

Range: 0.01 to 1.0

Default: 0.5

Sets the alpha factor of the Root Nyquist or Nyquist filter.

Filter Coefficient

Opens a Filter Editor window where you can import, export, and edit filter coefficients. A convenient plot of the filter's impulse response is displayed and updates as coefficients are changed. Imported and exported coefficient files are in text (*.txt) or comma-separated values (*.csv) format.

Bandwidth

Range: 1 kHz to Sample Rate

Default: 1 MHz

Sets the bandwidth for a low-pass filter.

BT

Range: 0.1 to 1.0

Default: 0.5

Sets the BT product of the Gaussian filter.

Length(symbol)

Range: 1 to 2048

Default: 32

Sets the length of the filter in symbols.

Add Segment

Choices: Data Segment | Idle Segment

Adds a segment row to the end of the segment table. Choose between data and idle segments.

Remove Segment

Removes the selected segment row from the segment table.

Move Up

Moves the selected segment row up one position in the segment table.

Move Down

Moves the selected segment row down one position in the segment table.

Name

Sets the name of the segment. Click on the name to edit.

Type

Displays the segment type: DATA or IDLE.

Number of Symbols

Range: 1 to 8388608

Default: 1000

Set the length of the segment in number of modulated symbols.

It's better to be an even number for Pi/4 DQPSK and Pi/8 D8PSK case for non-burst signal.

Ramp Samples

Range: 0 to 1000

Default: 0

Set the length of ramp samples for each data segment. Not configurable for idle segments.

Payload

Choices: PN9 | PN15 | PN23 | Custom Bit Pattern | User File

Default: PN9

Opens the Data Setup editor to configure payload bits.You can also load, save, and create custom bit patterns.

PN Seed is in hexadecimal format and is applicable only to PN types (PN9, PN15, and PN23).

Offset is in decimal format and is applicable to all data types (including PN9, PN15, PN23, custom pattern, and user file).

Constellation

Choices: BPSK | QPSK | 8PSK | 16QAM | 32QAM | 64QAM | 128QAM | 256QAM | 512QAM | 1024QAM | 2048QAM | 4096QAM | User defined

Default: 16QAM

Displays the modulation type for the segment. Click the cell to open the Constellation Setting window where you can customize the constellation.

Phase Rotation

Range: 0 to 360

Default: 0

Set an additional phase rotation applied to the constellation for the segment. To view the phase rotation, you can check the Show Rotation checkbox in the Constellation Setting window.

Shift

Enable or disable shift for phase rotation. When enabled, the phase rotation is only applied to the odd symbol. For example: pi/2 shift BPSK, pi/4 shift QPSK. When shift is enabled, differential and offset are disabled and set to false. When differential or offset is enabled, shift is disabled and set to false.

Bits Per Symbol

Displays the number of bits contained in one modulated symbol.

Differential

Enable or disable the differential encoding for the segment. This can be enabled only for BPSK, QPSK, and 8PSK constellations. Differential and Offset modes cannot be enabled simultaneously.

Offset

Enable or disable IQ offset by half symbol time. This can only be enabled for a QPSK constellation. Differential and Offset modes cannot be enabled simultaneously.